We know that some genetically modified foods are designed to be pest-resistant, and were wondering about the mechanism - how do they do it?
We put this question to Dr Jim Haseloff, from Cambridge University:
Jim - Organic farmers actually use bacteria Ė the Bacillus thuringiensis bacterium which has a protein which affects the gut of specific insects and that protein, of course, is encoded in the gene and that gene can be then transferred to plants using genetic engineering techniques. So itís essentially a surgical procedure of isolating the particular gene using a natural bacterium to transfer that into a plant and then once itís in there, itís used as a gene thatís for breeding.
Chris - So presumably, with synthetic biology, what one would do is to say "rather than take that toxin from a bacterium, what would be better would be to study the organisms that we want to make the plant resistant to, and then find our own way of making the plant resistant" and put some kind of specific thing into the plant that will be even better than what a bacterium toxin could do for us.
Jim - Thatís certainly feasible in the longer term. I think most of the emphasis at this point is on better engineering using existing systems, existing parts from what we know in the biological world and rearranging their delivery inside say, for example a crop system, where you might get around some of the issues weíre talked about earlier in the program where youíve got some insects which are immune to these very specific toxins and can escape. So you can imagine a second element that would deal with that for example.
Sarah asked the Naked Scientists: Hi there, We know that some genetically modified foods are designed to be pest-resistant, and were wondering about the mechanism. My husband thinks that they are engineered to produce a pesticide (ie. a toxin). I think that it's more likely that the crops are engineered to produce a compound that is unpalatable to whatever insects typically eat them. Can you settle this debate? Many thanks! Sarah (Canada) What do you think? Sarah, Tue, 11th May 2010
The genes to encode a pesticide ( or a protein that is like a pesticide to the particular target) is selected from a donor organism that produces it naturally. This is then placed in the recipient cell by various methods, either via a virus or by injection or by explosive recombination.